A metal foil has a threshold frequency of 5.45 x 10^14 Hz. Which color of visible light will not eject electrons from this metal?
a) blue
b) indigo
c) violet
d) orange
c=(wavelength)(v)
3.0x10^8m/s = (wavelength)(5.45 x 10^14 Hz)
550 nm -> releases green. So, I am guessing the answer would be d) orange.
this wrong. the answer is Green, Blue, Indigo and violet
^nope, the tutor was in fact correct. blue, green, violet, and indigo ARE ejected. Orange, is not ejected. Read the question carefully, "which will NOT eject electrons."
To determine which color of visible light will not eject electrons from the metal foil, we need to compare the threshold frequency of the metal foil with the frequencies of different colors of visible light.
The threshold frequency is given as 5.45 x 10^14 Hz. The color of light with the highest frequency in the visible spectrum is violet, followed by indigo, blue, green, yellow, orange, and red.
To find the frequency of a color, we can use the equation c = λν, where c is the speed of light (approximately 3.0 x 10^8 m/s), λ is the wavelength of light, and ν (nu) is the frequency.
Now, let's determine the frequency for each color and compare it with the threshold frequency:
- Violet light has a wavelength of approximately 400 nm. Using the equation c = λν, we can find the frequency: ν = c / λ = (3.0 x 10^8 m/s) / (400 x 10^-9 m) ≈ 7.5 x 10^14 Hz.
Since the frequency of violet light is higher than the threshold frequency, it can eject electrons from the metal foil.
- Indigo light has a wavelength of approximately 450 nm. We can repeat the calculation to find its frequency: ν = c / λ = (3.0 x 10^8 m/s) / (450 x 10^-9 m) ≈ 6.7 x 10^14 Hz.
This frequency is also higher than the threshold frequency, meaning indigo light can eject electrons.
- Blue light has a wavelength around 500 nm. Calculating its frequency: ν = c / λ = (3.0 x 10^8 m/s) / (500 x 10^-9 m) = 6.0 x 10^14 Hz.
Again, the frequency of blue light is higher than the threshold, allowing it to eject electrons.
- Green light has a wavelength around 550 nm. Calculating its frequency: ν = c / λ = (3.0 x 10^8 m/s) / (550 x 10^-9 m) ≈ 5.5 x 10^14 Hz.
Here, the frequency of green light is equal to the threshold frequency, so it can eject electrons as well.
- Continuing this pattern, we have yellow light with a frequency higher than 5.45 x 10^14 Hz, so it can also eject electrons.
- Orange light has a wavelength of approximately 650 nm. Calculating its frequency: ν = c / λ = (3.0 x 10^8 m/s) / (650 x 10^-9 m) ≈ 4.6 x 10^14 Hz.
From this calculation, we can see that the frequency of orange light is lower than the threshold frequency of 5.45 x 10^14 Hz. Therefore, orange light will not have enough energy to eject electrons from the metal foil.
Hence, the correct answer is d) orange.